Uranium dioxide, which is a typical nuclear fuel material, is produced from uranium hexafluoride in a uranium nuclear fuel production plant. At the step where the intermediate produce ammonium diuranate is produced, a solution containing ammonium ions and fluoride ions is produced as a waste. Today this waste solution is treated with calcium hydroxide to cause separation into ammonia water and calcium fluoride in the uranium nuclear fuel production plant, and only ammonia water is recycled to the production of nuclear fuel material.
The calcium fluoride is simply stored and accumulated in the nuclear fuel production plant, since no way has been found for direct use of this material in the plant. Outside of the nuclear fuel production plant, calcium fluoride will be a starting material for the production of anhydrous hydrofluoric acid. In this case, however, additional processing is required in order to supply this material out of a nuclear fuel production plant as satisfactory raw material. The system therefor will be complicated. The production of hydrofluoric acid from calcium fluoride is accompanied by formation of a by-product which cannot be directly used.
This invention is directed to processing of a waste solution from a uranium nuclear fuel production plant containing ammonium fluoride and ammonia to recover fluorine material and ammonia material separately with minimum generation of waste materials, wherein the fluorine material can be recovered in the form of anhydrous hydrogen fluoride, which is a raw material for the uranium hexafluoride conversion. Further in the process of the present invention, the reagents used for the above separation can be recycled and reused after reprocessing, whereby the amount of the waste material is minimized. We, noting specific behavior of magnesium chloride, devised a combination of steps to achieve the above-mentioned object making use of the specific property of magnesium chloride and completed this invention.